Variable GraviTrax compatible spacer

This gravitrax spacer has variable height. The 4cm spacer you can see in the picture extends about 2.5cm, so it ranges from 4cm to 6.5cm. The 5cm spacer should extend to about 8cm, and so on.

If you want, you can add some more diameters in the diameters array to get more piles (and therefore more extension). But then every single pile will be very thin and therefore very fragile.

The design uses the very nice thread_profile.scad library which you can download here:
https://github.com/MisterHW/IoP-satellite/tree/master/OpenSCAD%20bottle%20threads
You only need to put the thread_profile.scad file in the "libraries" subfolder of your OpenSCAD installation.
The file thread_profile.scad in turn needs the packages https://github.com/openscad/scad-utils and https://github.com/openscad/list-comprehension-demos which you also put into the libraries subfolder of your OpenSCAD installation (in subfolders scad-utils and list-comprehension-demos, respectively).

I recommend a test print